Fish quality investigations using electrical impedance spectroscopy: preliminary results

Abstract

The consumption of seafood has increased over the last 10 years. This article analyses impedance changes of tilapia (Oreochromis niloticus) sample measured over 36 hours by using electrical impedance spectroscopy (EIS). It was also investigated the correlations between variables in order to predictive models to degradation studies. Measurements were collected every 12 hours in order to verify any change due to deterioration. The results show that measurements in both longitudinal and transverse axes are equivalent and that the sample undergoes gradual variations in the impedance. The first set of data collected in the frequency range from 0.1 to 1,000 kHz showed that resistance varied from 310.9 (@ 0.1 kHz) to 86.8 Ω (@1 MHz) and capacitive reactance varied from -8.6 to 11.5 Ω, respectively. The forth set of data showed a decrease of 79.3% (@0.1 kHz) in the resistance part of the impedance, whereas 98.8% in capacitive reactance at 0.1 kHz. These results might suggest that there was a nutritional loss of the sample over time. Further experiments must be done over a long period of time in order to fully understand the process. EIS might be pointed out as a potential technique for fish shelf live quality control.